The present invention relates to computer input devices. It finds particular application in conjunction with multi-axis direction and motion encoding and selection devices and will be described with particular reference thereto.
Heretofore, two and three-dimensional trackballs have been readily available. Typically, a two-dimensional trackball was supported on two perpendicular rollers. Frictional engagement between the ball and the rollers caused rotation of the ball to be translated into corresponding rotation of each roller. More specifically, the rotation of each roller was indicative of rotation of the ball relative to an axis parallel to the central axis of the roller. Encoders were connected with each roller to convert the rotation of the corresponding roller into electrical signals, e.g. an electrical pulse signal for each increment of rotation. For a three-dimensional trackball, a third roller was typically positioned orthogonal to the other two to contact a side of the trackball.
Commonly, the trackball has been utilized to move a curser to selected regions of a video display. Upon reaching a desired position, e.g. a menu selection, the operator lifted his hand from the trackball and depressed a nearby selection button to indicate selection of the menu item associated with the curser.
One of the problems with lifting one's hand from the trackball is that the hand motion sometimes applied rotational forces to the ball causing it to reposition itself, i.e. the cursor moved.
Other operators maintained contact with the trackball with the palm of the hand or some fingers while reaching for the selection button with another finger. In this manner, the operator was able to maintain continued contact with the trackball, hence continuous positional control of the cursor. However, reaching for the selection button sometimes caused unwanted rotation of the trackball.
Not only was the separate selection device, typically a pushbutton, cumbersome, it was also more expensive to manufacture and produce.
The present invention contemplates a new and improved integrated trackball and selection device which overcomes the above-referenced problems and others.